Everyone knows the tantrum that happens when you take the screen away. But by that point, your kid has been overstimulated for a while. The signs show up earlier if you know what to look for.
1. The glazed stare
There's a difference between a kid who's engaged and a kid who's zoned out. Engaged looks like: leaning in, tapping with purpose, reacting to what happens on screen. Zoned out looks like: slack jaw, no movement, eyes fixed but not really seeing.
The glazed stare usually means the content has outpaced their ability to process it. Their brain has switched from active engagement to passive reception. This is more common with video content than interactive games, but it can happen with anything if the session goes long enough.
2. Getting physical
Toddlers who are overstimulated start moving in ways that don't match the activity. Bouncing, flapping, kicking, rolling around while still holding the device. Their nervous system is trying to discharge energy that the screen experience is building up but not releasing.
This is different from the excited wiggling of a kid who's having fun. It's more erratic, and it usually escalates. If your kid is getting increasingly fidgety while watching or playing, that's their body saying "I've had enough" before their mouth does.
3. Can't transition
If you gently mention that screen time is ending soon and your kid immediately escalates (crying, grabbing, refusing to make eye contact), that's a sign the session has gone past the point where their brain can handle the transition.
A kid who's been watching or playing for the right amount of time might grumble, but they can shift. A kid who's deep in overstimulation can't access the self-regulation needed to let go. The longer the session, the harder the landing.
What to do about it
You don't need to set rigid timers. Just watch your kid. When you see any of these three signs, start the wind-down. Use the transition techniques that work for your family.
Over time, you'll get a feel for your kid's window. Some 2-year-olds max out at 10 minutes. Some 4-year-olds are fine for 30. The number matters less than reading the signals.